Exploding stars ending worlds

[robrob]

Ok here we go.<br /><br />I have wondered recently, after a session involving mushrooms, a palace on a hill and a night full of stars, of the possibility of worlds being destroyed as we speak. Bear with me here, honestly.<br /><br />Now I don’t know the exact nature of exploding stars, but I imagine if you are life on a planet closeby, or close enough, when a star goes bang, then you’ve had it. Seeing as the Universe is, for want of a better word, big, there are obviously a lot of stars at different stages of their lives. There must be millions coming to the end of their lives too, surely? And they will explode, obliterating anything nearby.<br /><br />Therefore, there must be worlds with civilisations being wiped out by these exploding stars. I’m not talking like one every second, but surely every week or month one will go? After all, we cannot comprehend the size of the Universe or just how many stars with nearby planets there is.<br />

 

[najab]

Probably, yes.

 

[robrob]

Well honestly, upon pondering that I really have to take a few minutes, that is really something to take in, very humbling indeed.

 

[nexium]

I agree, very humbling. If there are a million times a million times a million = 10E18 O,B,A and F stars with intelegent civilizations (within 5 light years)(in the Universe) and these go super nova after one billion years on the average; one billion civilizations are destroyed per year! Planets around nearby stars are typically sterilized by a super nova blast, so the number may not be high even if intelegent life orbiting massive stars is rare. Also stars with less mass sometimes flare up, and numerous other kinds of catastrophe do occur. Neil

 

[centsworth_II]

Civilizations around the universe (if they exist) are being wiped out all the time, and the end of their star's (sun's) life is probably far down the list of causes. Advanced life on our own planet will probably be wiped out long before the end of the Sun's life several billion years from now. More likely causes of demise include: The explosion of a nearby star -- not the planet's own sun. Attack by a killer meteor or comet. And the old standby, self-imposed thermonuclear annihilation. <div class="Discussion_UserSignature"> </div>

 

[tomnackid]

Even civilizations in nearby solar systems would be destroyed or severely damaged by an Supernova. If Proxima Centari were to go supernova it would certainly sterilize all life in our solar system.

 

[robrob]

Thats 31 a second then, jesus.<br /><br />And let's apply it to any stars, not just their own.<br /><br />Crazyness.

 

[nexium]

Are you saying A and F stars don't have enough mass to super nova? The O and A stars produce more ultra violet and X rays than they do visable light, so photo synthesis may be impossible. Advanced colonys might be possible several astronomical units from the star. Neil

 

[mikeemmert]

I think it's important to know not only what can destroy Earth, but also what can't. And supernovae are just not on that list.<br /><br />Remember, brightness falls off as the square of the distance. Proxima Centauri, a common red dwarf, is about 250,000 AU from earth, so any object at that distance would have to be about 62 billion times brighter than the sun to give the same radiation flux as the sun, thus doubling the amount of energy recieved. That's just about how much brighter than the Sun a supernova is in visible and infrared light.<br /><br />Supernovae progenitors, O or B stars, are very rare and it's not likely one would be our closest star. If it were four times the distance, it would be about 16 times dimmer than the sun and wouldn't hurt us.<br /><br />I have heard of another destructive mechanism; supernovae are much brighter in neutrinos than in visible light. After reading that article, I thought, "There's a way to check that".<br /><br />Shelton's Supernova, SN 1987A, exploded 170, 000 light years away. 26 neutrinos were detected from that event. If it were 17 light years away, it would be 100,000,000 times brighter, which would result in 2.6 billion neutrinos being detected.<br /><br />Now, 2.6 billion uranium fissions will not produce enough energy to hurt you, and uranium fissions are much more energetic than neurtrinos. Uranium atoms are tiny! Plus, those 26 neutrinos were absorbed by thousands of gallons of water, and humans don't have thousands of gallons of material, so there would be considerably fewer than 2.6 billion neutrinos absorbed by human flesh.<br /><br />I think supernovae can be eliminated as a cause of mass extinctions on Earth. But we still have to worry about asteroid collisions (the Cretaceous-Tertiary extinction), extreme volcanic eruptions (like the Siberian Traps event which is now thought to be the cause of the Permian-Triassic extinction) and climate change (thought to have caused the Megafaunal extinction of the Wooly Mam

 

[spd405]

IIRC last year some of the earth's mass extinctions were found to be very close (as close as you can get geologically) to the timing of stars going bang - a gamma ray burst is the likley culprit if this is the case.